US8844126B2 - Method of manufacturing an electrical connector - Google Patents

Abstract

Electrical resistance between a male part and a female part through a canted spring is disclosed using mathematical modeling. Increase or decrease in resistance can be quickly analyzed by looking at the equivalence resistance and the number of contacts at the input side, the output side, or both. The number of contacts may also be created by forming a dimple having a discontinuity.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This is a regular utility application of provisional application No. 61/478,815, filed Apr. 25, 2011, and of provisional application Ser. No. 61/426,954, filed Dec. 23, 2010, the entire contents of each of which are expressly incorporated herein by reference.

BACKGROUND

Aspects of the disclosed embodiments relate to electrical connectors. Canted coil springs may be used to electrically connect two parts. A first part is a female part such that a bore extends through the part and can receive a second part, which is a male part. The male part may be shaped similar to a pin, shaft, plug, shank or the like and may have an outer surface with a shape corresponding to the shape of the bore. The outer diameter of the pin is smaller than the inner diameter of the bore to allow insertion of the pin into the bore and removal of the pin from the bore. The inner surface of the bore includes a groove for retaining a canted coil spring, which may instead be located on the pin and the combination configured to be inserted into the bore. In conventional current conducting applications of canted coil springs, the pin is inserted into the bore such that the outer surface of the pin contacts the canted coil spring. The canted coil spring establishes a connection between the outer surface of the pin and the inner surface of the bore. Accordingly, the canted coil spring facilitates flow of electrical current between the two parts.

SUMMARY

An electrical connector is provided. In one example, the connector comprises a piston, a housing, and a canted coil spring comprising a plurality of spring coils. Wherein a single groove is incorporated in the housing or in the piston but not both the housing and the piston. The single groove is configured for accommodating the canted coil spring. Wherein at least one of the spring coils has a dimple formed upon the coil to define a section having a discontinuity.

According to aspects of the disclosure, an electrical connector for electrical applications uses a canted coil spring between two components to transfer current between them. In one embodiment, at least one of the components has a V-shaped groove to contact at least one coil of the canted coil spring at two contact points. In another embodiment, both components include a V-shaped groove to provide multiple points of contact per coil for increased current carrying capability and decreased contact resistance. In yet another embodiment, both components have a curved groove to provide continuous contact surfaces with at least one coil of the spring. In yet another embodiment, one or both of the grooves are configured to reduce both contact resistance between the two components and the canted coil spring, and path resistance during transfer of electrical current through the canted coil spring from one component to the other component.

A method for increasing a number of contact points in a single groove electrical connector assembly is provided. The method comprising providing a housing; providing a piston; providing a canted coil spring having a plurality of spring coils; and providing a groove in the housing or in the piston but not both the housing and the piston. The groove being sized and configured for accommodating the canted coil spring. The method further comprising providing a dimple having a discontinuity formed upon at least one of the spring coils; and wherein the dimple forms two contact points when contacting the at least one of the spring coils with the dimple against a generally flat surface.

In another aspect of the present assembly, an electrical connector is provided comprising a piston, a housing, and a canted coil spring comprising a plurality of spring coils. A groove is incorporated in the housing or in the piston or both. The groove is configured for accommodating the canted coil spring and a separate groove may be incorporated adjacent the groove for accommodating another canted coil spring. Wherein at least one spring coil of the plurality of coils has a dimple formed thereon to define a section having a discontinuity.

In another example, all of the plurality of spring coils each comprising a dimple formed thereon to define a section having a discontinuity.

In another example, the spring is formed from a multi-metallic wire.

In another example, the housing has the groove and wherein the at least one of the spring coils has two contact points with the housing and two contact points with a generally planar surface on the piston.

In another example, the piston has the groove and wherein the at least one of the spring coils has two contact points with the piston and two contact points with a generally planar surface on the housing.

In still another example, an equivalent resistance for a circuit formed from the connector assembly is 50% less than an equivalent resistance formed from a circuit made from a similar connector assembly but without the dimple formed upon the coil.

In a further aspect of the present method, a method of forming a spring is provided. The method comprising the steps of forming a plurality of coils from a wire, canting the plurality of coils in a same canting direction, and forming a dimple on at least one coil of the plurality of coils to form a section having a discontinuity.

In yet another example, the method further comprises the step of forming a dimple on each of the plurality of coils.

In yet another example, the method further comprises the step of welding two end coils to from a garter-type canted coil spring.

In yet another example, the wire is made from a copper material.

In yet another example, the wire is made from a multi-metallic wire.

In yet another example, the multi-metallic wire comprises a copper inner core and a high tensile strength outer layer.

The method of forming the spring can further comprise the step of forming a second dimple on the at least one coil at a location opposite the dimple.

A still further aspect of the present method is a method of increasing a number of contact points in a spring groove comprising the steps of providing a housing; providing a piston; providing a canted coil spring having a plurality of spring coils; and forming a common groove between the housing and the piston. The common groove can comprise two side walls and a groove bottom located therebetween. The method further comprising the step of providing a dimple having a discontinuity formed upon at least one of the spring coils and wherein the dimple forms two contact points against a generally flat surface of the common groove.

In yet another example, the method further comprises the step of providing a dimple having a discontinuity formed upon all of the plurality of coils.

In yet another example, the method further comprises the step of providing a second dimple having a discontinuity formed upon the at least one of the spring coils at a location opposite the dimple.

In yet another example, the method further comprises the step of providing a second dimple having a discontinuity upon all of the plurality of coils.

The method can include providing the groove bottom on the piston and forming a V-groove with the two side walls in a bore of the housing.

The method can include providing the groove bottom in the housing and forming a V-groove with the two side walls on the piston.

The various embodiments of the present electrical connector have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the present embodiments as expressed by the claims that follow, their more prominent features now will be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of the present embodiments provide various advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments of the present electrical connector will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious electrical connector shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals indicate like parts:

FIG. 1 is a side cross-sectional view of an electrical connector according to one exemplary embodiment.

FIG. 2 is a front cross-sectional view of the electrical connector ofFIG. 1.

FIG. 3 is a diagram of an electrical circuit representing contact resistances of the electrical connector ofFIG. 1.

FIG. 4 is a side cross-sectional view of an electrical connector according to another exemplary embodiment.

FIG. 5 is a front cross-sectional view of the electrical connector ofFIG. 4.

FIG. 6 is a diagram of an electrical circuit representing contact resistances of the electrical connector ofFIG. 4.

FIG. 7 is a side cross-sectional view of an electrical connector according to another exemplary embodiment.

FIG. 8 is a front cross-sectional view of the electrical connector ofFIG. 7.

FIG. 9 is a diagram of an electrical circuit representing contact resistances of the electrical connector ofFIG. 7.

FIG. 10 is a front cross-sectional view of an electrical connector according to another exemplary embodiment.

FIG. 11 is an electrical circuit representing contact resistances and path resistances of the electrical connector ofFIG. 7.

FIG. 12 is a front cross-sectional view of an electrical connector according to another exemplary embodiment.

FIG. 13 is a front cross-sectional view of an electrical connector according to another exemplary embodiment.

FIG. 14 is a side partial cross-sectional view of an electrical connector according to yet another exemplary embodiment.

FIG. 15 is a side partial cross-sectional view of yet an electrical connector according to exemplary embodiment.

The following detailed description describes the present embodiments with reference to the drawings. In the drawings, reference numbers label elements of the present embodiments. These reference numbers are reproduced below in connection with the discussion of the corresponding drawing features.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of embodiments of an electrical connector with a canted coil spring and methods for using the same and are not intended to represent the only forms in which the present assemblies and methods may be constructed or used. The description sets forth the features and the steps for using and constructing an electrical connector with a canted coil spring and methods for using the same in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the assemblies and methods. As denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features.

FIGS. 1 and 2 show anelectrical connector10 according to one exemplary embodiment. The electrical connector includes aninput side12 and anoutput side14. Theinput side12 includes a generallyflat contact surface16. Theoutput side14 includes a generallyflat contact surface22. A cantedcoil spring30 connects theinput side12 to theoutput side14 and facilitates flow of electrical current from theinput side12 to theoutput side14. The cantedcoil spring30 is formed by a plurality ofcoils32 that are canted at an acute angle relative to a centerline

extending through the coils. The two end coils can be connected to form a garter-type spring. The canted coil springs discussed herein are similar to exemplary canted coil springs disclosed in U.S. Pat. Nos. 4,655,462; 4,826,144; 4,876,781; 4,907,788; 4,915,366; 4,961,253; 4,964,204; 5,139,243; 5,160,122; 5,503,375; 5,615,870; 5,709,371; 5,791,638; and 7,055,812 and in co-pending application Ser. No. 12/102,626, filed Apr. 14, 2008 and Ser. No. 12/767,421, filed Apr. 26, 2010, the contents of which are expressly incorporated herein by reference. Furthermore, the connectors discussed herein are similar to exemplary connectors disclosed in U.S. Pat. Nos. 4,678,210; 5,081,390; 5,411,348; 5,545,842; 6,749,358; 6,835.084; 7,070,455; and 7,195,523, the contents of which are expressly incorporated herein by reference.

Thecoils32 of the cantedcoil spring30 contact thecontact surface16 of theinput side12 at acontact point40. Thecoils32 of the cantedcoil spring30 contact thecontact surface22 of theoutput side14 at acontact point44. The point contact between the flat contact surfaces16 and22 and the circular or elliptical coils of the cantedcoil spring30 is referred to herein as a purely mathematical concept. One of ordinary skill in the art will readily recognize that the actual contact between the cantedcoil spring30 and theflat surfaces16 and22 occurs at small contact areas, respectively. Theinput side12 transfers electrical current to the cantedcoil spring30 through thecontact point40. Accordingly, the transfer of current at thecontact point40 creates a first contact resistance RC1. The cantedcoil spring30 then transfers the electrical current to theoutput side14 through thecontact point44. Accordingly, the transfer of current at thecontact point44 creates a second contact resistance RC2.FIG. 3 shows an equivalent circuit representing contact resistances RC1 and RC2. Contact resistances RC1 and RC2 are in series. Therefore, an approximate equivalent resistance. Req for the circuit ofFIG. 3 is computed using Ohm's Law and represented byequation 1 as follows:
Req˜RC1+RC2  (1)

Assuming that theinput side12 and theoutput side14 are constructed from the same materials and the contact points40 and44 are approximately the same size, then the resistances RC1 and RC2 may have substantially the same value, which is referred to herein as RC. Therefore, the equivalent resistance Req can be represented byequation 2 as follows:
Req˜2RC  (2)

FIGS. 4 and 5 show anelectrical connector100 according to a second exemplary embodiment. The electrical connector includes aninput side112 and anoutput side114. Theinput side112 includes afirst contact surface116 and asecond contact surface118 that are oriented at an angle α relative to each other, which are more clearly shown inFIG. 5. Accordingly, the contact surfaces116 and118 form a V-shaped groove or V-groove120, the depth of which partially depends on the magnitude of the angle α. Theoutput side114 includes aflat contact surface122. A cantedcoil spring130 connects theinput side112 to theoutput side114 and facilitates flow of electrical current from theinput side112 to theoutput side114. The cantedcoil spring130 is formed with a plurality ofcoils132 that are canted at an acute angle relative to a centerline

extending through the coils.

The V-shapedgroove120 of theinput side112 accommodates the cantedcoil spring130 such that the cantedcoil spring130 contacts thefirst contact surface116 at afirst contact point140 and contacts thesecond contact surface118 at asecond contact point142. The cantedcoil spring130 contacts thecontact surface122 of theoutput side114 at athird contact point144. Theinput side112 transfers electrical current to the cantedcoil spring130 through thefirst contact point140 and thesecond contact point142. Accordingly, the transfer of current at thefirst contact point140 creates a first contact resistance RC1. Similarly, the transfer of current at thesecond contact point142 creates a second contact resistance RC2. The cantedcoil spring130 then transfers the electrical current to theoutput side114 through thethird contact point144. Accordingly, the transfer of current at thethird contact point144 creates a third contact resistance RC3.

FIG. 6 shows an equivalent circuit representing contact resistances RC1, RC2 and RC3. Contact resistances RC1 and RC2 are in parallel, and contact resistance RC3 is in series with the equivalent resistance of RC1 and RC2. An approximate equivalent resistance Req of the circuit shown inFIG. 6 can be computed using Ohm's Law and represented byequation 3 as follows:

$\begin{array}{cc}\mathrm{Req}~\frac{\mathrm{RC}1\mathrm{RC}2}{\left(\mathrm{RC}1+\mathrm{RC}2\right)}+\mathrm{RC}3& \left(3\right)\end{array}$

Assuming that theinput side112 and theoutput side114 are constructed from the same materials, and the contact points140,142 and144 are approximately the same size, then the resistances RC1, RC2 and RC3 may have substantially the same value, which is referred to herein as RC. Therefore, Req can be represent by equation 4 as follows:
Req˜1.5RC  (4)

The equivalent resistance of the circuit inFIG. 6 is about 25% less than the equivalent resistance of the circuit inFIG. 3 by having theinput side112 contact the cantedcoil spring130 at two contact points rather than only one. Accordingly, theelectrical connector100 is more efficient in conducting current than theelectrical connector10. However, in certain applications the higher equivalent resistance provided by theconnector10 may be preferred. For example, an application may require a certain level of heat to be generated at the electrical connector. Accordingly, theconnector10 may be more suitable for such applications as compared to theconnector100, because the higher equivalent resistance of theconnector10 causes more heat generation than the heat generation caused by the equivalent resistance of theconnector100.

If theinput side112 contacts the cantedcoil spring130 at more than two contact points, then by designating n as the number of contact points between theinput side112 and the cantedcoil spring130, and assuming that all of the contact points have the same contact resistance RC, then the equivalent contact resistance Req of theconnector100 can be approximately represented by equation 5 as follows:

$\begin{array}{cc}\mathrm{Req}~\frac{n+1}{n}\mathrm{RC}n=2,3,4,\dots & \left(5\right)\end{array}$

Based on equation 5, when theinput side112 contacts the cantedcoil spring130 at two contact points. Req˜1.5 RC, which is the scenario discussed above in the embodiment ofFIGS. 4 and 5. As the number of contact points on theinput side112 increases, Req falls between 1 and 1.5, with Req˜1 for a very large number of contact points. Thus, one of ordinary skill in the art will recognize that the larger the number of contact points between theinput side112 and the cantedcoil spring130, the lower the equivalent contact resistance of theelectrical connector100 compared to similar structured connectors but with fewer contacts on the input side.

FIGS. 7 and 8 show anelectrical connector200 according to a third exemplary embodiment. The electrical connector includes aninput side212 and anoutput side214. Theinput side212 includes afirst contact surface216 and asecond contact surface218 that are oriented at an angle α relative to each other. Accordingly, the contact surfaces216 and218 form a V-shaped groove or V-groove220, the depth of which partially depends on the magnitude of the angle α. Theoutput side214 includes afirst contact surface222 and asecond contact surface224 that are oriented at an angle β relative to each other. Accordingly, the contact surfaces222 and224 form a V-shapedgroove226, the depth of which partially depends on the magnitude of the angle β. A cantedcoil spring230 connects theinput side212 to theoutput side214 and facilitates flow of electrical current from theinput side212 to theoutput side214. The cantedcoil spring230 is formed with a plurality of coils232 (one coil shown inFIG. 5) that are canted at an acute angle relative to a centerline

extending through the coils.

The V-shapedgroove220 of theinput side212 accommodates the cantedcoil spring230 such that the cantedcoil spring230 contacts thefirst contact surface216 at afirst contact point240 and contacts thesecond contact surface218 at asecond contact point242. The V-shapedgroove226 of theoutput side214 accommodates the cantedcoil spring230 such that the cantedcoil spring230 contacts thefirst contact surface222 at athird contact point244 and contacts thesecond contact surface224 at afourth contact point246. Theinput side212 transfers electrical current to the cantedcoil spring230 through thefirst contact point240 and thesecond contact point242. Accordingly, the transfer of current at thefirst contact point240 creates a first contact resistance RC1. Similarly, the transfer of current at thesecond contact point242 creates a second contact resistance RC2. Electrical current from cantedcoil spring230 is transferred to theoutput side214 through thethird contact point244 and thefourth contact point246. Accordingly, the transfer of current at thethird contact point244 creates a third contact resistance RC3. Similarly, the transfer of current at thefourth contact point246 creates a fourth contact resistance RC4.

FIG. 9 shows an equivalent circuit representing contact resistances RC1, RC2, RC3 and RC4. An approximate equivalent resistance Req of the circuit shown inFIG. 9 can be computed using Ohm's Law and represented by equation 6 as follows:

$\begin{array}{cc}\mathrm{Req}~\frac{\left(\mathrm{RC}1+\mathrm{RC}3\right)\left(\mathrm{RC}2+\mathrm{RC}4\right)}{\left(\mathrm{RC}1+\mathrm{RC}2+\mathrm{RC}3+\mathrm{RC}4\right)}& \left(6\right)\end{array}$

Assuming that theinput side212 and theoutput side214 are constructed from the same materials, and the contact points240,242,244 and246 are approximately the same size, then the resistances RC1, RC2, RC3 and RC4 may have substantially the same value, which is referred to herein as RC. Therefore, Req can be represent by equation 7 as follows:
Req˜RC  (7)

The equivalent resistance of the circuit inFIG. 9 is approximately 33% less than the equivalent resistance of the circuit inFIG. 6 by having theoutput side214 contact the cantedcoil spring230 at two contact points rather than only one. Furthermore, the equivalent resistance of the circuit inFIG. 9 is about 50% less than the equivalent resistance of the circuit inFIG. 3, because each of theinput side212 and theoutput side214 contacts the cantedcoil spring230 at two contact points rather than only one. Accordingly, theelectrical connector200 is more efficient than theelectrical connector100 and theelectrical connector10 at transferring current from the input side to the output side. However, in certain applications the higher equivalent resistance provided by theconnector10 or theconnector100 may be preferred. For example, an application may require a certain level of heat to be generated at the electrical connector. Accordingly, theelectrical connector10 or theelectrical connector100 may be more suitable for such applications as compared to theconnector200, because the higher equivalent resistances of theconnector10 or theconnector100 causes more heat generation than the heat generation caused by the equivalent resistance of theconnector200.

Based on the above, one of ordinary skill in the art will appreciate that the number of contacts between a canted coil spring, the input side and the output side can affect the equivalent resistance of the electrical connector. The greater the number of contacts between the canted coil spring, the input side and the output side, the lower the equivalent resistance of the electrical connector. In the embodiments ofFIGS. 7-9, up to two contacts on the input side and two contacts on the output side are provided. For example, if up to four contacts on the input side and four contacts on the output side are provided, the equivalent contact resistance of the electrical connector is approximately 0.5 RC, assuming that contact resistances at all of the contacts are generally similar.

FIG. 10 shows anelectrical connector300 according to one exemplary embodiment. The electrical connector includes an input orinput side312 and an output oroutput side314. Theinput side312 includes a generallycurved contact surface316. Theoutput side314 also includes a generallycurved contact surface322. A cantedcoil spring330 connects theinput side312 to theoutput side314 and facilitates flow of electrical current from theinput side312 to theoutput side314. The cantedcoil spring330 is formed by a plurality of coils332 (one coil shown inFIG. 10) that are canted at an acute angle relative to a centerline

(shown extending through the page inFIG. 10) extending through the coils.

The cantedcoil spring330 may contact theentire contact surface316 and theentire contact surface322, especially when theinput side312 and theoutput side314 compress the cantedcoil spring330. In other words, theelectrical connector300 provides a lame number of contact points between the cantedcoil spring330, theinput side312 and theoutput side314 as compared to theelectrical connectors10,100 and200. Accordingly, the equivalent contact resistance of theelectrical connector300 is less than the equivalent contact resistances of theelectrical connectors10,100 and200.

In the embodiment ofFIG. 10, theinput side312 and theoutput side314 contact the cantedcoil spring330 at a large number of contact points. Designating n as the number of contact points on each of theinput side312 and theoutput side314, and assuming that all contact points have the same contact resistance, the equivalent contact resistance of theconnector300 can be approximately represented by equation 8 as follows:

$\begin{array}{cc}\mathrm{Req}~\frac{2}{n}\mathrm{RC}n=2,3,4,\dots & \left(8\right)\end{array}$

Based on equation 8, when each of theinput side312 and theoutput side314 contacts the cantedcoil spring330 at two contact points. Req˜1, which is the scenario discussed above in the embodiment ofFIGS. 7 and 8. As the number of contact points on each of theinput side312 and theoutput side314 increases, Req falls between 0 and 1, with the Req approaching zero for a very large number of contact points (i.e., Req˜0 when n=∞ in a purely mathematical model of the electrical connector). Thus, one of ordinary skill in the art will recognize that the larger the number of contact points between theinput side312 and the cantedcoil spring330 and theoutput side314 and the cantedcoil spring330, the lower the equivalent contact resistance of theelectrical connector300.

The exemplary electrical connectors disclosed herein may be used in any application where electrical current is transferred from one part to another with a canted coil spring. For example, the input side can be a bore of an electrical outlet or socket and the output side can be the shaft of an electrical plug. Other non-limiting examples include a stem from a car battery and a clamp from a car engine, and an audio jack and an audio transmitter. Heat transfer properties of the electrical connectors discussed herein are analogous to their contact resistance properties. Accordingly, the same principles regarding efficient transfer of current depending on the extent of contact between the spring, the input side and the output side are equally applicable to heat transfer between these parts. For example, heat is transferred more efficiently from the input side to the output side through thespring330 of theelectrical connector300 ofFIG. 10 thanspring230 of theelectrical connector200 ofFIGS. 7-9. Similarly, heat is transferred more efficiently from the input side to the output side through thespring230 of theelectrical connector200 ofFIGS. 7-9 than thespring130 of theelectrical connector100 ofFIGS. 4-6. Thus, the present disclosure is not limited to electrical connectors and is applicable to connections for heat transfer from one part to another.

In the above embodiments only contact resistances are discussed, which are created because of the contact between the input side and the canted coil spring and between the output side and the canted coil spring. Referring for example to the embodiments ofFIGS. 7 and 8, thecoils232 of the spring also create a path resistance as the current flows through thecoils232 from theinput side212 to theoutput side214. This path resistance is referred to herein as RP.FIG. 11 is a circuit diagram that illustrates both the contact resistances RC and path resistances RP of theelectrical connector200 ofFIGS. 7 and 8. Referring toFIG. 8, the section P1 of thecoil232 between thecontact point240 and thecontact point244 creates a path resistance RP1 as current flows from thecontact point240 to contactpoint244. Similarly, the section P2 of thecoil232 between thecontact point242 and thecontact point246 creates a path resistance RP2 as current flows from thecontact point242 to contactpoint246. Assuming that the coil sections P1 and P2 have the same geometry, have the same dimensions, and are constructed from the same materials, the values of RP1 and RP2 largely dependent on the length of the sections P1 and P2, respectively. Accordingly, the closer the contact points are to each other, the lower the path resistance will be between theinput side212 and theoutput side214. The resistance created due to flow of electrical current through the canted coil spring from the input side to the output side is further described in co-pending patent application Ser. No. 12/691,564, filed Jan. 21, 2010, the contents of which are expressly incorporated herein by reference.

FIG. 11 illustrates an equivalent circuit representing contact resistances RC1, RC2, RC3 and RC4, and path resistances RP1 and RP2. An approximate equivalent resistance Req of the circuit shown inFIG. 11 can be computed using Ohm's Law and represented by equation 9 as follows:

$\begin{array}{cc}\mathrm{Req}~\frac{\left(\mathrm{RC}1+\mathrm{RP}1+\mathrm{RC}3\right)\left(\mathrm{RC}2+\mathrm{RP}2+\mathrm{RC}4\right)}{\left(\mathrm{RC}1+\mathrm{RC}2+\mathrm{RC}3+\mathrm{RC}4+\mathrm{RP}1+\mathrm{RP}2\right)}& \left(9\right)\end{array}$

Assuming that theinput side212 and theoutput side214 are constructed from the same materials, and the contact points240,242,244 and246 are approximately the same size, then the resistances RC1, RC2, RC3 and RC4 may have substantially the same value, which is referred to herein as RC. Also, assuming that the sections P1 and P2 of thecoil232 have the same length, have the same geometry, have the same dimensions, and are constructed from the same materials, then RP1 and RP2 have substantially the same value, which is referred to herein as RP. Therefore, equation 9 can be rewritten as follows:
Req˜RC+0.5RP  (10)

The analysis provided above can be similarly applied to the other embodiments disclosed herein. Accordingly, the equivalent resistance for any electrical connector having two parts connected with a spring can be computed using Ohm's Law. Furthermore, an electrical connector can be designed to have a preferred equivalent resistance depending on the application in which the electrical connector is utilized. For example, for an application that requires an electrical connector with as low an equivalent resistance as possible, the number of contact points are increased (e.g. see the embodiment ofFIG. 10) and/or the distance between the contact points are reduced in order to reduce the path resistance. In contrast, for an application that requires an electrical connector with a high equivalent resistance, the number of contact points is reduced and/or the distance between the contact points are increased in order to increase the path resistance.

As discussed below, increasing the number of contact points to reduce contact resistance does not necessarily lead to reduced path resistance or vice versa. Referring toFIG. 12, anelectrical connector400 is shown having a large number of contact points in a contact area CI because of substantially continuous contact between theinput side412 and the cantedcoil spring430. Theoutput side414 contacts the cantedcoil spring430 at acontact point444. A section P1 of acoil432 extends from anedge440 of the contact area CI to thecontact point444 with a radial length L1. A section P2 extends between anedge442 of the contact area CI to thecontact point444 with a radial length L2. Referring toFIG. 13, anelectrical connector500 is shown having twocontact points540 and542 between theinput side512 and the cantedcoil spring530. Theoutput side514 contacts the cantedcoil spring530 at acontact point544. The section P1 of thecoil532 extends betweencontacts540 and544 with a radial length L1, and the section P2 of thecoil532 extends betweencontacts542 and544 with a radial length L2. The equivalent contact resistance in the embodiment ofFIG. 12 is less than the equivalent contact resistance in the embodiment ofFIG. 13 because theinput side412 contacts thespring430 with a larger number of contact points than the number of contact points between theinput side512 and thespring530. However, the equivalent path resistance in the embodiment ofFIG. 12 is greater than the equivalent path resistance in the embodiment ofFIG. 13 because the radial lengths L1 and L2 of the sections P1 and P2, respectively, of thecoil432 are greater than the radial lengths L1 and L2 of the sections P1 and P2, respectively, of thecoil532. Thus, one of ordinary skill in the art will recognize from the exemplary embodiments ofFIGS. 12 and 13 that an electrical connector can be designed to provide a preferred contact and/or path resistance properties that are suitable for a particular application.

FIG. 14 is a side partial cross-sectional view of anelectrical connector assembly600 according to yet another exemplary embodiment. Theelectrical assembly600 may be referred to as a connector for a holding application incorporating asingle groove602. As shown, thegroove602 is located on or in thehousing604 and not the piston orshaft606. Thegroove602 on thehousing604 includes afirst contact surface616 and asecond contact surface618 that are oriented at an angle to one another to form a V-groove. However, other groove configurations having two slanted surfaces are contemplated.

When in use as an electrical connector, electrical current transferring to or from thehousing604 to the cantedcoil spring630 having a spring coil632 as shown passes through twocontact points640,642 located between the housing and the canted coil spring. Accordingly, the transfer of current at thefirst contact point640 creates a first contact resistance RC1 and transfer of current at thesecond contact point642 creates a second contact resistance RC2.

Although thecurrent assembly600 incorporates asingle groove602, similar to theassembly100 ofFIG. 5, two additional contact points644,646 are provided between the spring coil632 and thesurface622 of thepiston606 to form a four contact point electrical connector. More specifically, the present assembly, device and method incorporate four contact points in a single groove holding application. For asingle coil232, the four contact points are defined by two coil-to-housing contact points,640,642 and two coil-to-piston contact points644,646. Accordingly, the transfer of current at thethird contact point644 creates a first contact resistance RC3 and transfer of current at thefourth contact point646 creates a fourth contact resistance RC4.

Thus, although only a single groove is used in the present assembly and device, like the assembly ofFIG. 5, the current assembly has the same equivalent resistance Req as the circuit shown inFIG. 9 and is approximately 33% less than the equivalent resistance of the circuit inFIG. 6, which is the equivalent circuit for the assembly ofFIG. 5. In one embodiment, thethird contact point644 and thefourth contact point646 are formed by creating a dimple orarcuate surface670 on the coil632. For example, the coil can be subjected to pressure or impact against an anvil, pressurized by a specially designed clamp, or other post coffin treatment processes. The dimple orarcuate surface670 creates a section having a discontinuity formed upon the coil. The discontinuity alters the curvature of the coil to create multiple contact points between the coil and the piston. In the present embodiment, two contact points are created by the discontinuity.

As understood, the present assembly, device, and method incorporate twocontact points644,646 between a spring coil632 and asurface622, such as a surface of a piston, and wherein thesurface672 is generally constant or flat between the two contact points. In an alternative embodiment, a complex groove may be incorporated on the piston, similar to a Mansard roof with a flat bottom and two tapered side surfaces, to provide four contact points between the spring coil and the piston, with two created by the dimple on the coil and two by the geometry of the Mansard roof.

Thus, an aspect of the present method is further understood to include a method for forming a canted coil spring comprising coiling a wire to from a plurality of coils and canting the coils to cant along the same orientation. Forming a dimple on each of the plurality of coils to create coils with discontinuities for forming two contact points for each coil with a flat surface. The end coils can be welded to form a garter-type spring. In one example, the dimples can be created by pressuring or impacting the coils against one or more anvils. The anvils can have different sizes so that the dimples can be progressively formed to their final configuration. In another example, the coils can be pressurized by a specially designed clamp or other post coiling treatment processes.

FIG. 15 is a side partial cross-sectional view of anelectrical connector assembly700 according to yet another exemplary embodiment. Theelectrical assembly700 may be referred to as a connector for a holding application incorporating asingle groove702 and is similar to theassembly600 ofFIG. 14. However, in the present embodiment, thespring730 having aspring coil732 with a dimple orarcuate surface770 is piston mounted. That is, thespring730 is mounted in agroove702 of apiston706 as opposed to ahousing704. The housing has a generally flat surface. Although only a single groove is provided, four contact points are incorporated in the present embodiment. Furthermore, thepresent spring730 and thespring630 ofFIG. 14 may be used in a two-groove configuration, with a groove in the housing and in or on the piston. Still furthermore, more than one spring may be used in parallel to decrease resistance. For example, twogrooves602 or702 may be used side-by-side with twosprings630 or730 in each of the grooves. In another embodiment, thegroove602 or702 has a continuous contact surface with thecoil632 or732, similar to the embodiment ofFIG. 10 or12. Still furthermore, two dimples may be formed on each coil of the plurality of coils. The two dimples on each coil is preferably located at opposed positions or locations on each coil.

In still yet another embodiment, a canted coil spring is provided having a plurality of coils. Wherein at least one of the coils of the plurality of coils incorporates a dimple defining a section of discontinuity formed upon the coil. In a prefer embodiment, a majority of the coils each having a dimple defining a section of discontinuity formed upon each coil. In yet another embodiment, all of the coils of the plurality of coils have a dimple defining a section having a discontinuity formed upon each coil.

The material from which the canted coil springs discussed above is constructed affects both the contact resistance and path resistance for the above-discussed electrical connectors depending on the operating environment of the electrical connectors. For example, a highly electrically conductive material such as copper provides a lower contact resistance and a lower path resistance than steel. Thus, the use of copper for the canted coil spring would be preferred for efficient electrical conduction. However, in certain applications, a canted coil spring formed entirely from copper may not be suitable. Most materials with high electrical conductivity have a relatively low melting point, resulting in limited temperature resistance and therefore limited applications. Accordingly, canted coil springs made of these highly conductive materials may lose a significant portion of their mechanical properties at high temperatures, thereby causing the locking mechanism or the electrical contact to become less effective or fail altogether. The decrease in strength limits the force that can be applied to electrically conductive canted coil springs, thereby also limiting the use of these canted coil springs in certain applications, especially those applications that require high mechanical forces in environments with elevated temperatures. The canted coil springs of the above embodiments can be made in a multi-metallic configuration having a temperature resistant metallic core such as steel with a highly conductive outer layer such as copper. Alternatively, the core can be constructed from a highly conductive material such as copper, and the outer layer can be constructed from a temperature resistant material such as steel. The canted coil spring can also be constructed from more than two metallic or non-metallic layers in various configurations in order to provide preferred operational properties for an electrical connector in which the canted coil spring is used. For example, a third corrosion resistant layer may be incorporated to limit corrosion. Further details about constructing a canted coil spring from multiple materials can be found in U.S. Patent Publications 2008/0254670, 2010/0029145, and 2010/0289198, the disclosures of which are expressly incorporated herein by reference.

One of ordinary skill in the art will readily recognize that the number of contact points may increase with the compression of the spring due to an increase in the contact area between the spring and the input side and/or the output side. The path resistance of the electrical connector may also decrease because of the compression of the spring. Thus, the operative compression range of the spring can be designed to provide preferred contact and/or path resistances for the electrical connector.

Accordingly, as understood from the present disclosure, a connector may be provided with relatively low electrical resistance by increasing the number of contacts, decreasing the path of resistance, incorporating multi-metallic materials, or combinations thereof to produce a low system resistance compared to similarly structured connectors without similar use of contacts, lower path resistance, and/or multi-metallic materials. Another feature of the present disclosure is the use of closely-spaced coils to provide more contact points than comparable canted coil springs with greater coil spacing.

The above description presents the best mode contemplated for the electrical connectors, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use these connections. The electrical connectors, however, are susceptible to modifications and alternate constructions from that discussed above that are equivalent. Consequently, the electrical connectors are not limited to the particular embodiments disclosed. Furthermore, features, aspects, or functions specifically discussed for one embodiment but not another may similarly be incorporated in the latter provided the features, aspects and/or functions are compatible. For example, a connector may have both a continuous section contacting between a coil and a housing and as well as spaced apart contacts. Thus, the disclosure covers all modifications and alternate constructions coming within the spirit and scope of the disclosure as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of the disclosure.

Claims (18)

What is claimed is:

1. A method of manufacturing an electrical connector with an equivalent resistance comprising:

providing a housing made from, at least in part, an electrically conductive material;

providing a pin made from, at least in part, an electrically conductive material;

positioning a canted coil spring comprising a spring coil in a groove, said groove being associated with the housing, the pin, or both; and

counting a first set of number of contact point or points between the spring coil and the housing and a second set of number of contact point or points between the spring coil and the pin;

using Ohm's Law, the first set of number of contact point or points, and the second set of number of contact point or points to compute the equivalent resistance for the electrical connector.

2. The method of manufacturing ofclaim 1, further comprising associating the groove with the housing only.

3. The method of manufacturing ofclaim 1, further comprising associating the groove with the pin only.

4. The method of manufacturing ofclaim 1, wherein the first set of number of contact point or points is one, and the second set of number of contact point or points is one.

5. The method of manufacturing ofclaim 1, wherein the first set of number of contact point or points or the second set of number of contact point or points is two by forming a V-shape bottom wall in the groove.

6. The method of manufacturing ofclaim 1, wherein the first set of number of contact point(s) or the second set of number of contact point or point is two by forming a dimple on the coil to define a section having a discontinuity.

7. The method of manufacturing ofclaim 1, wherein the first set of number of contact point or points or the second set of number of contact point or points is two by forming the groove with two tapered sidewalls relative to a bottom wall.

8. The method of manufacturing ofclaim 1, wherein the contact between the spring coil and the housing or between the spring coil and the pin is along an arc length of the coil.

9. The method of manufacturing ofclaim 1, further comprising determining a first path length of the spring coil between the housing and the pin and a second path length of the spring coil between the housing and the pin.

10. The method of manufacturing ofclaim 9, further comprising using Ohm's Law, the first path length of the spring coil between the housing and the pin, and the second path length of the spring coil between the housing and the pin to compute the equivalent resistance for the electrical connector.

11. A method of manufacturing an electrical connector with an equivalent resistance comprising:

providing a housing made from, at least in part, an electrically conductive material;

providing a pin made from, at least in part, an electrically conductive material;

positioning a canted coil spring comprising a spring coil in a groove, said groove being associated with the housing, the pin, or both;

counting a first set of number of contact point or points between the spring coil and the housing and a second set of number of contact point or points between the spring coil and the pin; and

determining a first path length of the spring coil between the housing and the pin and a second path length of the spring coil between the housing and the pin;

using Ohm's Law, the first set of number of contact point or points, the second set of number of contact point or points, the first path length of the spring coil between the housing and the pin, and the second path length of the spring coil between the housing and the pin to compute the equivalent resistance for the electrical connector.

12. The method of manufacturing ofclaim 11, further comprising associating the groove with the housing only.

13. The method of manufacturing ofclaim 11, further comprising associating the groove with the pin only.

14. The method of manufacturing ofclaim 11, wherein the first set of number of contact point or points is one, and the second set of number of contact point or points is one.

15. The method of manufacturing ofclaim 11, wherein the first set of number of contact point or points or the second set of number of contact point or points is two by forming a V-shape bottom wall in the groove.

16. The method of manufacturing ofclaim 11, wherein the first set of number of contact point or points or the second set of number of contact point or points is two by forming a dimple on the coil to define a section having a discontinuity.

17. The method of manufacturing ofclaim 11, wherein the first set of number of contact point or points or the second set of number of contact point or points is two by forming the groove with two tapered sidewalls relative to a bottom wall.

18. The method of manufacturing ofclaim 11, wherein the contact between the spring coil and the housing or between the spring coil and the pin is along an arc length of the coil.

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